Manufacturing method of light-emitting device
A method of manufacturing a light-emitting device is disclosed. The method includes providing a light-emitting diode wafer, including a substrate and a semiconductor stack on the substrate, wherein the semiconductor stack has a lower surface facing the substrate and an upper surface opposite to the lower surface; providing a first laser on the light-emitting diode wafer and irradiating the light-emitting diode wafer from the upper surface to form a plurality of scribing lines on the upper surface; providing an etching process; providing and focusing a second laser on an interior of the substrate to form one or a plurality of textured areas in the substrate; and providing force on the light-emitting diode wafer to separate the light-emitting diode wafer into a plurality of light-emitting diode chips along the plurality of scribing lines.
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This application is a continuation application of U.S. patent application Ser. No. 15/626,993, filed on Jun. 19, 2017, which is a divisional application of U.S. patent application Ser. No. 14/796,166, filed on Jul. 10, 2015, which claims priority to and the benefit of Taiwan Application Serial Number 103124086 filed on Jul. 11, 2014, which is incorporated by reference in its entirety.
BACKGROUND Technical FieldThe present disclosure relates to a light-emitting diode device and a manufacturing method thereof, more particularly, to a light-emitting diode wafer dicing technology.
Description of the Related ArtLight-emitting diode (LED) is an optoelectronic device composed of p-type semiconductor and n-type semiconductor. LEDs emit light by combination of the carriers on p-n junction and can be widely applied in optical display devices, traffic signals, data storage devices, communication devices, lighting devices and medical instruments. Conventional process of manufacturing LEDs includes forming a semiconductor stack on a substrate by epitaxy process so as to form a wafer. After the epitaxy process, a dicing process is performed to divide the wafer into a plurality of light-emitting diode chips.
Conventional wafer dicing method includes forming two groups of scribing lines which are perpendicular to each other on the surface of the LED wafer, and then performing cleaving process by using a saw along the two groups of the scribing lines to split the wafer into a plurality of LED chips along the scribing lines. However, the yield of the conventional dicing method is degraded when the thickness of substrate increases. Besides, debris or particles generated during the dicing process may easily remain on the LED chip and then absorb light. As a result, light extraction and brightness of the LED deteriorate.
SUMMARY OF THE DISCLOSUREA method of manufacturing a light-emitting device is disclosed. The method includes providing a light-emitting diode wafer, including a substrate and a semiconductor stack on the substrate, wherein the semiconductor stack has a lower surface facing the substrate and an upper surface opposite to the lower surface; providing a first laser on the light-emitting diode wafer and irradiating the light-emitting diode wafer from the upper surface to form a plurality of scribing lines on the upper surface; providing an etching process; providing and focusing a second laser on an interior of the substrate to form one or a plurality of textured areas in the substrate; and providing force on the light-emitting diode wafer to separate the light-emitting diode wafer into a plurality of light-emitting diode chips along the plurality of scribing lines.
Reference is made in detail to the preferred embodiments of the present application, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts.
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In another embodiment of manufacturing method for light-emitting diode chip of the present application, similarly, the wafer with a substrate which has thickness not smaller than 150 μm is irradiated by the first laser, and repeated stealth dicing lasers are applied to the second surface of the substrate. In order to avoid the semiconductor stack being damaged by the scattering from the laser, the power of the stealth dicing laser which focuses on an interior position of the substrate more close to the semiconductor stack 20 is smaller than that of the stealth dicing laser which focuses on an interior position of the substrate more far away from the semiconductor stack 20; the dicing speed of the stealth dicing laser which focuses on a position more close to the semiconductor stack 20 is faster than the dicing speed of the stealth dicing laser which focuses on other position of the substrate more far away from the semiconductor stack 20. That is, when practicing the stealth dicing laser at the position of the substrate which is close to the semiconductor stack 20, a laser with low power and high speed is applied. In one embodiment, the power of the stealth dicing laser ranges from 0.05 Watt to 0.15 Watt, and the dicing speed ranges from 400 mm/sec to 1000 mm/sec.
In the embodiments of present application, the substrate with a thickness not smaller than 150 μm is used to gain more light-extraction area and light-extraction angle. The laser dicing process with once or repeated stealth dicing laser can improve the yield. Besides, the textured areas on the side surface of the substrate can regulate the morphology of lateral of the LED chip, and internal total reflection caused by the smooth surface can be prevented so the light extraction and scattering from the lateral of the chips are enhanced. Thus, light extraction efficiency in whole LED chips is improved.
It will be apparent to those having ordinary skill in the art that various modifications and variations can be made to the devices in accordance with the present disclosure without departing from the scope or spirit of the disclosure. In view of the foregoing, it is intended that the present disclosure covers modifications and variations of this disclosure provided they fall within the scope of the following claims and their equivalents.
Claims
1. A method of manufacturing a light-emitting device, comprising:
- providing a light-emitting diode wafer, comprising a substrate and a semiconductor stack on the substrate, wherein the semiconductor stack has a lower surface facing the substrate and an upper surface opposite to the lower surface;
- providing a first laser on the light-emitting diode wafer and irradiating the light-emitting diode wafer from the upper surface to form a plurality of scribing lines on the upper surface;
- providing an etching process to clean the light-emitting diode wafer after providing the first laser;
- forming an electrode on the semiconductor stack after providing the first laser;
- providing and focusing a second laser on an interior of the substrate to form one or a plurality of textured areas in the substrate; and
- providing force on the light-emitting diode wafer to separate the light-emitting diode wafer into a plurality of light-emitting diode chips along the plurality of scribing lines.
2. The method of claim 1, wherein a thickness of the substrate is not smaller than 150 μm and a number of the textured area(s) is N; and wherein N is not greater than a value rounded up to integer of (thickness of the substrate−100)μm/50.
3. The method of claim 1, wherein a distance between the lower surface of the semiconductor stack and the textured area which is closest to the semiconductor stack is not smaller than 80 μm.
4. The method of claim 1, wherein after separating the light-emitting diode wafer into the plurality of light-emitting diode chips, a surface roughness parameter RRMS of one of the light-emitting diode chips at the textured area ranges between 1 μm to 5 μm.
5. The method of claim 1, wherein after separating the light-emitting diode wafer into the plurality of light-emitting diode chips, a thickness of the substrate is not smaller than 150 μm.
6. The method of claim 1, wherein the step of providing and focusing the second laser on the interior of the substrate comprises performing the second laser in the substrate multiple times to form the plurality of textured areas on a same cross section of the substrate; and wherein the second laser is a stealth dicing laser.
7. The method of claim 6, wherein the step of performing the second laser in the substrate multiple times to form the plurality of textured areas comprises:
- performing a first stealth dicing laser with a first power in the substrate with a first focused position; and
- performing a second stealth dicing laser with a second power in the substrate with a second focused position;
- wherein the first focused position in the substrate is closer to the semiconductor stack than the second focused position, the first power is lower than the second power.
8. The method of claim 7, wherein the first power ranges from 0.05 W to 0.15 W.
9. The method of claim 1, wherein the textured area is substantially parallel to the upper surface and/or the lower surface in a side view, wherein the textured area comprises a plurality of textured stripes.
10. The method of claim 9, wherein after separating the light-emitting diode wafer into the plurality of light-emitting diode chips, the textured area has a width which is smaller than 60 μm along a thickness direction of the substrate.
11. The method of claim 1, further comprising forming a reflective structure on a surface of the substrate opposite to the semiconductor stack.
12. The method of claim 1, wherein the etching process is a wet-etching.
13. The method of claim 1, wherein the first laser cuts through a portion of the semiconductor stack to form the plurality of scribing lines.
14. The method of claim 1, wherein the first laser forms a first region on a side surface of the substrate; and wherein after separating the light-emitting diode wafer into the plurality of light-emitting diode chips, and a surface roughness parameter RRMS of one of the light-emitting diode chips at the textured area is larger than that of the first region.
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Type: Grant
Filed: Oct 12, 2018
Date of Patent: Mar 17, 2020
Patent Publication Number: 20190051791
Assignee: EPISTAR CORPORATION (Hsinchu)
Inventors: Po-Shun Chiu (Hsinchu), De-Shan Kuo (Hsinchu), Jhih-Jheng Yang (Hsinchu), Jiun-Ru Huang (Hsinchu), Jian-Huei Li (Hsinchu), Ying-Chieh Chen (Hsinchu), Zi-Jin Lin (Hsinchu)
Primary Examiner: Matthew L Reames
Application Number: 16/159,251